The present invention relates generally to new and novel improvements in an apparatus and method for leveling the clamping surface to obtain proper heat sink for narrow strips in a coil end joiner. More particularly, the present invention relates to an apparatus and method for leveling the clamping surface to obtain proper heat sink for narrow strips in a coil end joiner which facilitates the positioning of the coil ends in a coil end joiner to provide substantially edge-to-edge weld penetration in a coil end to coil end weld joint.
In many metalworking operations involving stamping, forming or otherwise processing a metallic material provided in a coil configuration, it is desirable to join the trailing end of a coil about to be depleted with the leading end of a new coil to facilitate the metalworking operations. For example, if coil material is being fed through a press or some other piece of metalworking equipment, it is often desirable to have an "endless" supply of material to reduce or eliminate the necessity of "rethreading" the coil material when a coil is depleted. In the past, various types of coil end joiners have been used to join the trailing end of a coil about to be depleted with the leading end of a new coil to provide such an "endless" supply of material.
Many prior art coil end joiners butt up the trailing edge of a coil about to be depleted with the leading edge of a new coil and join the two (2) coil ends together, typically using an arc welding process, such as gas tungsten arc welding (GTAW), or perhaps more commonly known as tungsten inert gas (TIG) welding. Prior to the arc welding process, the trailing edge of the coil about to be depleted is butted up with the leading edge of the new coil and both the trailing edge of the coil about to be depleted and the leading edge of the new coil are typically positioned against a stop in the rear portion of the coil end joiner table. The trailing edge of the coil about to be depleted and the leading edge of the new coil are then typically held in position for the arc welding process by a retaining plate which is moved downwardly against the trailing edge of the coil about to be depleted and the leading edge of the new coil by one or more air cylinders. When the coil material being joined is sufficiently wide, the retaining plate which is moved downwardly against the trailing edge of the coil about to be depleted and the leading edge of the new coil engages a sufficient portion of the coil material such that the retaining plate is substantially level and an acceptable coil end arc weld joint is achieved. However, if the coil material being joined is relatively narrow, the retaining plate which is moved downwardly against the trailing edge of the coil about to be depleted and the leading edge of the new coil may tilt and engage the front edge of the coil material and a forward portion of the coil end joiner support table, thus resulting in the retaining plate being tilted in relation to the coil end joiner support table and the coil material being joined. This may result in the retaining plate being positioned above all of the coil material being joined, with the exception of the front edge of the coil material being joined where there is contact between the retaining plate and the coil material being joined. Such tilting of the retaining plate often results in "burnout/suck back" occurring at or near the start of the coil end arc weld joint, insufficient cooling of the coil end arc weld and, in general, an unsatisfactory coil end arc weld joint.
For example, in FIG. 1, a coil end arc weld is shown where the retaining plate was tilted, resulting in a substantially circular "keyhole burnout/suck back" portion being present near the start of the coil end arc weld joint. A second example is shown in FIG. 2, where a coil end arc weld was made with the retaining plate tilted, resulting in a substantially semi-circular "burnout/suck back" portion being present extending to the initial edge of the coil material at the start of the coil end arc weld joint. On the other hand, FIG. 3 shows a coil end arc weld joint which was made with the retaining plate held substantially level and substantially edge-to-edge coil end arc weld joint penetration is achieved.
While the coil end arc weld joints shown in FIGS. 1 and 2 could perhaps be tolerated in some metalworking operations, other metalworking operations either require, or would benefit, from a substantially edge-to-edge coil end arc weld joint. For example, a trend in many metalworking operations is to strive to utilize a greater percentage of the raw material in end products and reduce the remaining "skeleton" web of scrap metal as much as possible. Thus, many stamping operations, such as the stamping of motor laminations, utilize either the entire width or substantially the entire width of the coil material to fabricate the end product. If such a product is stamped across a coil end arc weld joint having a substantially circular "keyhole burnout/suck back" portion, as shown in FIG. 1, or a substantially semi-circular "burnout/suck back" portion, as shown in FIG. 2, the end product would be defective and, perhaps in most cases, would have to be scrapped. Further, in other metalworking forming operations, such as forming a coil material into an end product having a tubular configuration, all of the coil material is utilized in the end product. Thus, an end product having a substantially circular "keyhole burnout/suck back" portion, as shown in FIG. 1, or a substantially semi-circular "burnout/suck back" portion, as shown in FIG. 2, would be defective and, in most cases, would have to be scrapped. Furthermore, in some metalworking operations, it is necessary or desirable to maintain a continuous "skeleton" web to, for example, provide for continuous "pull-through" of the "skeleton" web.
In addition to the substantially circular "keyhole burnout/suck back" portion, as shown in FIG. 1, or a substantially semi-circular "burnout/suck back" portion, as shown in FIG. 2, which sometimes occurs at the start of a coil end arc weld joint made with the retaining plate tilted, a significant build-up of metallic material can occur at the start of the coil end arc weld joint. Such a build-up of metallic material can have a negative effect on subsequent feeding, machining, tooling and/or other manufacturing operations and, if nothing else, is unsightly in a final end product and may necessitate further end product rework and/or repair operations.
In the past, in order to maintain the retaining plate substantially level when relatively narrow coil material is being joined, a piece of the parent coil material being joined has sometimes been manually positioned on a forward portion of the coil joiner support table so the retaining plate contacts the trailing edge of the coil material about to be depleted, the leading edge of the new coil material and the manually placed coil material to provide for a substantially level retaining plate. Such manual placement of coil material on the coil joiner support table is, at best, time consuming, and may expose the operator to possible injury since the coil material has to be manually placed between the coil joiner support table and the retaining plate prior to the coil end arc welding process and the coil material has to be manually removed after the coil end arc weld joint has been completed.
Accordingly, an object of the present invention is to provide an apparatus and method for leveling the clamping surface to obtain proper heat sink for narrow strips in a coil end joiner which facilitates maintaining a retaining plate substantially level during a coil end arc welding process, particularly when joining coil material which is relatively narrow.
Another object of the present invention is the provision of an apparatus and method for leveling the clamping surface to obtain proper heat sink for narrow strips in a coil end joiner which is economical to fabricate and maintain and which is easy to use.
These and other objects of the present invention are attained by an apparatus and method for leveling the clamping surface to obtain proper heat sink for narrow strips in a coil end joiner which includes a coil material support table and a retaining plate which is positioned against the upper surface of the coil material to be joined by, for example, one or more air cylinders. A weld clamp leveler is also provided which is adjustable to provide a preselected offset between the coil material support table and the retaining plate in a forward portion of the coil material support table. The weld clamp leveler is preferably used when relatively narrow coil material is being joined to preclude tilting of the retaining plate relative to the coil material support table and the coil material being joined and is preferably adjusted to provide approximately the same offset between the coil end support table and the retaining plate as the thickness of the coil material being joined. On the other hand, when coil material which is sufficiently wide to preclude tilting of the retaining plate is being joined, the weld clamp leveler is disengaged and does not interfere with the coil end arc welding operation.
Other advantages and novel features of the present invention will become apparent in the following detailed description of the invention when considered in conjunction with the accompanying drawings.